In general, when a station (also commonly referred to as a mobile device, a mobile station, a mobile, a user, a subscriber, a terminal, and the like) enters a coverage area of an existing extended service set (ESS), the station performs an initial link setup to establish wireless local area network (LAN) connectivity. The initial link setup normally involves the station performing a scan to discover access points (APs). APs may also be commonly referred to as base terminal stations (BTS), base stations, controllers, communications controllers, and the like.
According to the IEEE 802.11 technical standards, there are two scanning techniques: passive scanning and active scanning. In passive scanning, a station waits until a next beacon frame is transmitted and based on the reception of the next beacon frame, discovers APs and initiates the initial link setup with an association procedure. It is noted that a beacon frame or beacon for short may be a form of a management packet. Therefore, the terms beacon frame, beacon, and management packet may be used interchangeably herein. In active scanning, a station transmits a message (such as a probe request message) that includes a service set identifier with which the station wants to associate. APs receiving the message respond with information needed by the station to perform the association procedure.
Task Group ai (TGai) of IEEE 802 has established a need for Fast Initial Link Setup (FILS). The work scope for TGai include improvements for AP/network discovery, secure authentication, and a mechanism to support concurrency in the exchange of higher layer protocol messages during an authentication phase. A target delay for AP/network discovery and secure authentication is less than 100 msec. However, a normal beacon interval is on the order of 100 msec, so target delay typically cannot be met with existing passive scanning as specified in the IEEE 802.11 technical standards.